Conventionally, for example in the pneumatic tire (radial tire) disclosed in Japanese Unexamined Patent Application Publication No. H11-28911A, it is an object to both reduce noise outside the vehicle and improve the wet road surface running performance. This pneumatic tire includes a tread pattern that includes a plurality of main grooves extending in the tire circumferential direction and lateral grooves intersecting the main grooves on a tread ground contact portion, and a plurality of notch grooves extending from buttress portions on the tire outer side in the shoulder portions located outer than main grooves on the outermost side to the inside of the shoulder portions and terminating in a closed manner. A half or more of the number of the notch grooves is configured so that length (L) from the ground contact edge (P) of the tread ground contact portion to the closed end is set to 50 to 90% of distance (K) from the ground contact edge (P) to the main groove on the outermost side. Note that this pneumatic tire has main grooves provided on the innermost side in the tire width direction and has lateral grooves provided in a zigzag manner in land portions located adjacent to the outer sides in the tire width direction of the main grooves, forming triangular block-like land portions.
Further, it is an object of the pneumatic tire (pneumatic tire for passenger car) disclosed in Japanese Unexamined Patent Application Publication No. H07-40714A to allow reduction of the ply steer residual component cornering force and steering wheel flow amount. This pneumatic tire has a block pattern on a tread surface that includes a plurality of main grooves that extend in the tire circumferential direction, and a multiplicity of subsidiary grooves that are arranged parallel to each other and intersect the main grooves at an inclination, forming a multiplicity of rhombic blocks. In this pneumatic tire, sipes are provided in at least rhombic blocks arranged in a ground contact center region of the tread surface, the sipes each connecting two points Q, Q′ distanced from the two obtuse angle points P, P′ of the rhombic block along the subsidiary groove side of the rhombic block by 0.20≦d/D≦0.50 and 0.20≦d′/D≦0.50 where D is the width of the block, and the angle of the sipes with respect to the tire circumferential direction is 5° or more.
The pneumatic tire of Japanese Unexamined Patent Application Publication No. H11-28911A as described above has main grooves provided on the innermost side in the tire width direction and lateral grooves provided in a zigzag manner in the land portions located adjacent to the outer sides in the tire width direction of the main grooves, forming triangular block-like land portions. Therefore, in the pneumatic tire of Japanese Unexamined Patent Application Publication No. H11-28911A as described above, the block rigidity is reduced in the center portion in the tire width direction, so the steering stability performance and the uneven wear resistance performance during high-speed traveling tends to deteriorate.
Further, in the pneumatic tires of Japanese Unexamined Patent Application Publication Nos. H11-28911A and H07-40714A as described above, the lateral grooves or the subsidiary grooves provided between the main grooves are formed with equal width. Therefore, the water drainage characteristics, in other words the wet performance, tends to be inferior in the center portion in the tire width direction.